File redaction database system

ABSTRACT

An example operation may include one or more of determining, by a file redaction device, redacted segments of a source file, receiving, by a signature update device, the redacted source file segments, a stored trapdoor key, and stored auxiliary data segments, determining modified auxiliary data from the redacted source file segments, the trapdoor key and the auxiliary data segments, executing chaincode to obtain a modified auxiliary data signature and identifiers of the redacted source file segments, and storing the modified auxiliary data signature and identifiers of the redacted source file segments to a shared ledger of a blockchain network. Each stored auxiliary data segment including a random string of data corresponding to a segment of the source file.

TECHNICAL FIELD

This application generally relates to a database storage system, andmore particularly, to a file redaction database system.

BACKGROUND

A centralized database stores and maintains data in one single database(e.g., database server) at one location. This location is often acentral computer, for example, a desktop central processing unit (CPU),a server CPU, or a mainframe computer. Information stored on acentralized database is typically accessible from multiple differentpoints. Multiple users or client workstations can work simultaneously onthe centralized database, for example, based on a client/serverconfiguration. A centralized database is easy to manage, maintain, andcontrol, especially for purposes of security because of its singlelocation. Within a centralized database, data redundancy is minimized asa single storing place of all data also implies that a given set of dataonly has one primary record.

However, a centralized database suffers from significant drawbacks. Forexample, a centralized database has a single point of failure. Inparticular, if there are no fault-tolerance considerations and ahardware failure occurs (for example a hardware, firmware, and/or asoftware failure), all data within the database is lost and work of allusers is interrupted. In addition, centralized databases are highlydependent on network connectivity. As a result, the slower theconnection, the amount of time needed for each database access isincreased. Another drawback is the occurrence of bottlenecks when acentralized database experiences high traffic due to a single location.Furthermore, a centralized database provides limited access to databecause only one copy of the data is maintained by the database. As aresult, multiple devices cannot access the same piece of data at thesame time without creating significant problems or risk overwritingstored data. Furthermore, because a database storage system has minimalto no data redundancy, data that is unexpectedly lost is very difficultto retrieve other than through manual operation from back-up storage.

Conventionally, a centralized database is limited by centralized controland approval, which makes such a system vulnerable to tampering andunauthorized file modifications. As such, what is needed is a solutionto overcome these significant drawbacks.

SUMMARY

One example embodiment provides a system that includes a blockchainnetwork, which includes a shared ledger, a file creation device, and asignature generation device. The file creation device is configured tocreate a source file. The signature generation device is configured tosegment the source file into source file segments, create a number ofauxiliary data segments that correspond to source file segments, performa chameleon hash of the source file segments and the auxiliary datasegments, obtain a source file signature from the chameleon hash,perform a cryptographic hash of the auxiliary data segments, obtain anauxiliary data signature from the cryptographic hash, and store thesource file and cryptographic signatures to the shared ledger. Eachauxiliary data segment includes a random string of data that correspondsto a source file segment.

Another example embodiment provides a method that includes one or moreof creating a source file, segmenting the source file into source filesegments, creating a number of auxiliary data segments corresponding tosource file segments, performing a chameleon hash of the source filesegments and the auxiliary data segments, obtaining a source filesignature from the chameleon hash, performing a cryptographic hash ofthe auxiliary data segments, obtaining an auxiliary data signature fromthe cryptographic hash, and storing the source file and cryptographicsignatures to a shared ledger of a blockchain network. Each auxiliarydata segment includes a random string of data that is generated based ona corresponding source file segment.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of creating a source file, segmentingthe source file into source file segments, creating a number ofauxiliary data segments corresponding to source file segments,performing a chameleon hash of the source file segments and theauxiliary data segments, obtaining a source file signature from thechameleon hash, performing a cryptographic hash of the auxiliary datasegments, obtaining an auxiliary data signature from the cryptographichash, and storing the source file and cryptographic signatures to ashared ledger of a blockchain network. Each auxiliary data segmentincludes a random string of data that is generated based on acorresponding source file segment.

One example embodiment provides a system that includes a blockchainnetwork, a file redaction device, and a signature update device. Theblockchain network includes a shared ledger. The file redaction deviceis configured to determine redacted segments of a source file. Thesignature update device is configured to receive the redacted sourcefile segments, receive a stored trapdoor key and stored auxiliary datasegments, determine modified auxiliary data from the redacted sourcefile segments, the trapdoor key and the auxiliary data segments, executechaincode to obtain a modified auxiliary data signature and identifiersof the redacted source file segments, and store the modified auxiliarydata signature and identifiers of the redacted source file segments tothe shared ledger. Each auxiliary data segment includes a random stringof data that corresponds to a segment of the source file

Another example embodiment provides a method that includes one or moreof determining, by a file redaction device, redacted segments of asource file, receiving, by a signature update device, the redactedsource file segments, a stored trapdoor key, and stored auxiliary datasegments, determining modified auxiliary data from the redacted sourcefile segments, the trapdoor key and the auxiliary data segments,executing chaincode to obtain a modified auxiliary data signature andidentifiers of the redacted source file segments, and storing themodified auxiliary data signature and identifiers of the redacted sourcefile segments to a shared ledger of a blockchain network. Each storedauxiliary data segment including a random string of data correspondingto a segment of the source file.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of determining, by a file redactiondevice, redacted segments of a source file, receiving, by a signatureupdate device, the redacted source file segments, a stored trapdoor key,and stored auxiliary data segments, determining modified auxiliary datafrom the redacted source file segments, the trapdoor key and theauxiliary data segments, executing chaincode to obtain a modifiedauxiliary data signature and identifiers of the redacted source filesegments, and storing the modified auxiliary data signature andidentifiers of the redacted source file segments to a shared ledger of ablockchain network. Each stored auxiliary data segment including arandom string of data corresponding to a segment of the source file.

One example embodiment provides a system that includes a blockchainnetwork, including a shared ledger, and a file verification device. Thefile verification device is configured to initiate verification of asource file or a redacted source file, execute one of a smart contractor chaincode to verify the chameleon hash signature and the auxiliarydata hash signature, and provide a notification whether the verificationwas successful or unsuccessful to a user who initiates verification. Inresponse to the file verification device initiates verification of thesource file, the file verification device is further configured toreceive stored source file segments and stored auxiliary data segments,generate a chameleon hash signature from the stored source file segmentsand the stored auxiliary data segments, and generate an auxiliary datahash signature from the stored auxiliary data segments. In response tothe file verification device initiates verification of the redactedsource file, the file verification device further is configured toreceive stored redacted file segments, stored auxiliary data segments,and stored modified auxiliary data, generate a chameleon hash signaturefrom the stored redacted file segments and stored auxiliary datasegments, and generate an auxiliary data hash signature from the storedmodified auxiliary data.

Another example embodiment provides a method that includes one or moreof initiating, by a file verification device, verification of a sourcefile or a redacted source file, executing one of a smart contract orchaincode to verify the chameleon hash signature and the auxiliary datahash signature, and providing a notification whether the verificationwas successful or unsuccessful to a user initiating verification. Inresponse to the file verification device initiating verification of thesource file, the method further includes the file verification devicereceiving stored source file segments and stored auxiliary datasegments, generating a chameleon hash signature from the stored sourcefile segments and the stored auxiliary data segments, and generating anauxiliary data hash signature from the stored auxiliary data segments.In response to the file verification device initiating verification ofthe redacted source file, the method further includes the fileverification device receiving stored redacted file segments, storedauxiliary data segments, and stored modified auxiliary data, generatinga chameleon hash signature from the stored redacted file segments andstored auxiliary data segments, and generating an auxiliary data hashsignature from the stored modified auxiliary data.

A further example embodiment provides a non-transitory computer readablemedium comprising instructions, that when read by a processor, cause theprocessor to perform one or more of initiating, by a file verificationdevice, verification of a source file or a redacted source file,executing one of a smart contract or chaincode to verify the chameleonhash signature and the auxiliary data hash signature, and providing anotification whether the verification was successful or unsuccessful toa user initiating verification. In response to the file verificationdevice initiating verification of the source file, the method furtherincludes the file verification device receiving stored source filesegments and stored auxiliary data segments, generating a chameleon hashsignature from the stored source file segments and the stored auxiliarydata segments, and generating an auxiliary data hash signature from thestored auxiliary data segments. In response to the file verificationdevice initiating verification of the redacted source file, the methodfurther includes the file verification device receiving stored redactedfile segments, stored auxiliary data segments, and stored modifiedauxiliary data, generating a chameleon hash signature from the storedredacted file segments and stored auxiliary data segments, andgenerating an auxiliary data hash signature from the stored modifiedauxiliary data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a logic network diagram of a system for securelystoring source media files to a blockchain, according to exampleembodiments.

FIG. 1B illustrates sanitizable signature generation for a file in ablockchain, according to example embodiments.

FIG. 1C illustrates a logic network diagram of a system for securelyredacting source media files to a blockchain, according to exampleembodiments.

FIG. 1D illustrates sanitizable signature redaction for a file in ablockchain, according to example embodiments.

FIG. 1E illustrates a logic network diagram of a system for securelyverifying source media files from a blockchain, according to exampleembodiments

FIG. 2A illustrates an example peer node configuration, according toexample embodiments.

FIG. 2B illustrates a further peer node configuration, according toexample embodiments.

FIG. 3 illustrates a permissioned network, according to exampleembodiments.

FIG. 4A illustrates a system messaging diagram for performing sourcefile signature generation, according to example embodiments.

FIG. 4B illustrates a system messaging diagram for performing sourcefile signature redaction, according to example embodiments.

FIG. 4C illustrates a system messaging diagram for performing signatureverification, according to example embodiments.

FIG. 5A illustrates a flow diagram of an example method of creatingsource file signatures in a blockchain, according to exampleembodiments.

FIG. 5B illustrates a flow diagram of an example method of creating aredacted source file signature in a blockchain, according to exampleembodiments.

FIG. 5C illustrates a flow diagram of an example method of verifyingsource and redacted file signatures in a blockchain.

FIG. 5D illustrates a flow diagram of an example method of redacting adocument associated with a blockchain transaction, according to exampleembodiments.

FIG. 6A illustrates an example system configured to perform one or moreoperations described herein, according to example embodiments.

FIG. 6B illustrates a further example system configured to perform oneor more operations described herein, according to example embodiments.

FIG. 6C illustrates a smart contract configuration among contractingparties and a mediating server configured to enforce the smart contractterms on the blockchain according to example embodiments.

FIG. 6D illustrates an additional example system, according to exampleembodiments.

FIG. 7A illustrates a process of new data being added to a database,according to example embodiments.

FIG. 7B illustrates contents a data block including the new data,according to example embodiments.

FIG. 8 illustrates an example system that supports one or more of theexample embodiments.

DETAILED DESCRIPTION

It will be readily understood that the instant components, as generallydescribed and illustrated in the figures herein, may be arranged anddesigned in a wide variety of different configurations. Thus, thefollowing detailed description of the embodiments of at least one of amethod, apparatus, non-transitory computer readable medium and system,as represented in the attached figures, is not intended to limit thescope of the application as claimed but is merely representative ofselected embodiments.

The instant features, structures, or characteristics as describedthroughout this specification may be combined in any suitable manner inone or more embodiments. For example, the usage of the phrases “exampleembodiments”, “some embodiments”, or other similar language, throughoutthis specification refers to the fact that a particular feature,structure, or characteristic described in connection with the embodimentmay be included in at least one embodiment. Thus, appearances of thephrases “example embodiments”, “in some embodiments”, “in otherembodiments”, or other similar language, throughout this specificationdo not necessarily all refer to the same group of embodiments, and thedescribed features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

In addition, while the term “message” may have been used in thedescription of embodiments, the application may be applied to many typesof network data, such as, packet, frame, datagram, etc. The term“message” also includes packet, frame, datagram, and any equivalentsthereof. Furthermore, while certain types of messages and signaling maybe depicted in exemplary embodiments they are not limited to a certaintype of message, and the application is not limited to a certain type ofsignaling.

Example embodiments provide methods, systems, components, non-transitorycomputer readable media, devices, and/or networks, which provide adevice-based blockchain system.

A decentralized database is a distributed storage system which includesmultiple nodes that communicate with each other. A blockchain is anexample of a decentralized database which includes an append-onlyimmutable data structure resembling a distributed ledger capable ofmaintaining records between mutually untrusted parties. The untrustedparties are referred to herein as peers or peer nodes. Each peermaintains a copy of the database records and no single peer can modifythe database records without a consensus being reached among thedistributed peers. For example, the peers may execute a consensusprotocol to validate blockchain storage transactions, group the storagetransactions into blocks, and build a hash chain over the blocks. Thisprocess forms the ledger by ordering the storage transactions, as isnecessary, for consistency. In a public or permission-less blockchain,anyone can participate without a specific identity. Public blockchainsoften involve native cryptocurrency and use consensus based on variousprotocols such as Proof of Work (PoW). On the other hand, a permissionedblockchain database provides a system which can secure inter-actionsamong a group of entities which share a common goal but which do notfully trust one another, such as businesses that exchange funds, goods,information, and the like.

A blockchain operates arbitrary, programmable logic, tailored to adecentralized storage scheme and referred to as “smart contracts” or“chaincodes.” In some cases, specialized chaincodes may exist formanagement functions and parameters which are referred to as systemchaincode. Smart contracts are trusted distributed applications whichleverage tamper-proof properties of the blockchain database and anunderlying agreement between nodes which is referred to as anendorsement or endorsement policy. In general, blockchain transactionstypically must be “endorsed” before being committed to the blockchainwhile transactions which are not endorsed are disregarded. A typicalendorsement policy allows chaincode to specify endorsers for atransaction in the form of a set of peer nodes that are necessary forendorsement. When a client sends the transaction to the peers specifiedin the endorsement policy, the transaction is executed to validate thetransaction. After validation, the transactions enter an ordering phasein which a consensus protocol is used to produce an ordered sequence ofendorsed transactions grouped into blocks.

Nodes are the communication entities of the blockchain system. A “node”may perform a logical function in the sense that multiple nodes ofdifferent types can run on the same physical server. Nodes are groupedin trust domains and are associated with logical entities that controlthem in various ways. Nodes may include different types, such as aclient or submitting-client node which submits a transaction-invocationto an endorser (e.g., peer), and broadcasts transaction-proposals to anordering service (e.g., ordering node). Another type of node is a peernode which can receive client submitted transactions, commit thetransactions and maintain a state and a copy of the ledger of blockchaintransactions. Peers can also have the role of an endorser, although itis not a requirement. An ordering-service-node or orderer is a noderunning the communication service for all nodes, and which implements adelivery guarantee, such as a broadcast to each of the peer nodes in thesystem when committing transactions and modifying a world state of theblockchain.

A ledger is a sequenced, tamper-resistant record of all statetransitions of a blockchain. State transitions may result from chaincodeinvocations (i.e., transactions) submitted by participating parties(e.g., client nodes, ordering nodes, endorser nodes, peer nodes, etc.).A transaction may result in a set of asset key-value pairs beingcommitted to the ledger as one or more operands, such as creates,updates, deletes, and the like. The ledger includes a blockchain (alsoreferred to as a chain) which is used to store an immutable, sequencedrecord in blocks. The ledger also includes a state database whichmaintains a current state of the blockchain. There is typically oneledger per channel. Each peer node maintains a copy of the ledger foreach channel of which they are a member.

A chain is a transaction log which is structured as hash-linked blocks,and each block contains a sequence of N transactions where N is equal toor greater than one. The block header includes a hash of the block'stransactions, as well as a hash of the prior block's header. In thisway, all transactions on the ledger may be sequenced andcryptographically linked together. Accordingly, it is not possible totamper with the ledger data without breaking the hash links. A hash of amost recently added blockchain block represents every transaction on thechain that has come before it, making it possible to ensure that allpeer nodes are in a consistent and trusted state. The chain may bestored on a peer node file system (i.e., local, attached storage, cloud,etc.), efficiently supporting the append-only nature of the blockchainworkload.

The current state of the immutable ledger represents the latest valuesfor all keys that are included in the chain transaction log. Because thecurrent state represents the latest key values known to a channel, it issometimes referred to as a world state. Chaincode invocations executetransactions against the current state data of the ledger. To make thesechaincode interactions efficient, the latest values of the keys may bestored in a state database. The state database may be simply an indexedview into the chain's transaction log, it can therefore be regeneratedfrom the chain at any time. The state database may automatically berecovered (or generated if needed) upon peer node startup, and beforetransactions are accepted.

Some benefits of the instant solutions described and depicted hereininclude a new solution where a gap previously existed. Existingblockchain-based solutions for multimedia integrity verification do notallow modification of the content after the initial commitment. Thepresent application describes a novel blockchain-based solution thatsupports advanced integrity requirements such as authorized multimediacontent alteration (e.g., redaction of faces to protect the privacy ofindividuals) by its creator before the content is distributed, whilepreventing the end-users from reconstructing the redacted segments basedon the published commitment. The proposed solution employs a chameleonhash function to generate the initial commitment, which is stored on theblockchain. The auxiliary data required for the integrity verificationstep is retained by the content creator and only a signature of thisauxiliary data is stored on the blockchain. Any modifications to themultimedia content require only updating the signature of the auxiliarydata, which is securely recorded on the blockchain.

Blockchain is different from a traditional database in that blockchainis not a central storage but rather a decentralized, immutable, andsecure storage, where nodes must share in changes to records in thestorage. Some properties that are inherent in blockchain and which helpimplement the blockchain include, but are not limited to, an immutableledger, smart contracts, security, privacy, decentralization, consensus,endorsement, accessibility, and the like, which are further describedherein. According to various aspects, the blockchain-based fileintegrity processes are implemented due to immutability/accountability,smart contracts/chaincodes, privacy/hidden aspects,decentralized/distributed organization, and consensus, —which areinherent and unique to blockchain.

In particular, with respect to immutability/accountability, the presentapplication provides a solution that fundamentally relies on the factthat the commitments (content and auxiliary data signatures, i.e., theroot nodes of the two Merkle trees, as well as timestamps, and contentowner identity details) published on the blockchain are immutable/notchangeable.

With respect to smart contracts/chaincodes, they are used torecord/track both changes made to the content and to verify theintegrity of the content.

With respect to privacy/hidden aspects, one of the core challengessolved by the present application are ways to make public commitmentabout a multimedia content/document and making selective redactions tothe public commitment such that the actual content itself remainsprivate/hidden during the recited process.

With respect to decentralized and distributed aspects, by using thedecentralized/distributed nature of blockchain, the need for a singletrusted entity to manage the published commitments is provided, whichimproves the integrity verification service.

With respect to consensus, distributed consensus ensures that no singleentity in the blockchain network can modify the stored commitments onthe blockchain in an unauthorized manner.

One of the benefits of the example embodiments is that it improves thefunctionality of a computing system by not relying on a centralizeddatabase. While it is possible to implement this application on atraditional database instead of a blockchain, such a scenario wouldrequire a centralized trusted entity who can guarantee the integrity ofthe commitments stored on the database and perform redaction on behalfof the content owners. In many applications, there is no single entitywho can provide such a service and is fully trusted by all the playersin the ecosystem.

Through the blockchain system described herein, a computing system canperform functionality without a single point of compromise because ofthe mechanisms inherent to blockchain. For example, all transactions andtransaction results are stored in an immutable shared ledger by eachmajor component that is a blockchain peer. Tampering is readilydetectable as a shared ledger would not match other shared ledgers ofthe blockchain network. Instead of storing a regular cryptographic hashof the content on a database, the proposed application stores aredactable signature. This has two main advantages. Firstly, it becomespossible to make unauthorized modifications to the content withoutinvalidating the stored commitment. Secondly, the stored commitment isno longer susceptible to brute-force hash inversion attacks, especiallyif the original content has low entropy or randomness.

The example embodiments provide numerous benefits over a traditionaldatabase. For example, through the blockchain the embodiments providenew technical means to address issues encountered in storage andverification of redacted files. Meanwhile, a traditional database couldnot be used to implement the example embodiments because traditionaldatabases utilize centralized storage that may be tampered with and doesnot rely on all blockchain peers to reach consensus for newtransactions. Accordingly, the example embodiments provide for aspecific solution to a problem in the arts/field of secure document andfile control.

The example embodiments also change how data may be stored within ablock structure of the blockchain. For example, data and transactionsthat will be stored in the blockchain will be signatures (root nodes) oftwo Merkle trees, which constitute the redactable signatures of thecontent. Additionally, metadata about the content, including creator ID,device authentication details, timestamp of content creation, logs ofauthorized modifications, and user authentications may all be stored onthe blockchain.

The present application achieves the key functional requirements of (i)guaranteeing content integrity while allowing for declared modificationsto the content and (ii) content privacy. A dishonest creator may performunauthorized (not recorded on the blockchain) modifications to thecontent after making the initial commitment, without being detected bythe recipient. The content recipient cannot learn any information aboutthe original data contained in the redacted segments during signatureverification.

While significant advancements have been made in the field of multimediaforensics to detect altered content, existing techniques are mostlypassive as they rarely enable the content creator to prove the integrityof the released content. In many application scenarios, the creator hasa strong incentive to establish the provenance and integrity of themultimedia data created and released by him. Since blockchain technologyprovides an immutable distributed database, it is an ideal solution forreliably time-stamping content with its creation time and storing anirrefutable commitment of the content at the time of its creation.However, a blockchain-based approach does not allow modification of thecontent after the initial commitment. The present application describesa unique blockchain-based solution that supports advanced integrityrequirements such as authorized multimedia content alteration (e.g.,redaction of faces to protect the privacy of individuals) by its creatorbefore the content is distributed, while preventing the end-users fromreconstructing the redacted segments based on the published commitment.The proposed solution employs a chameleon hash function to generate theinitial commitment, which is stored on the blockchain. The auxiliarydata required for the integrity verification step is retained by thecontent creator and only a signature of this auxiliary data is stored onthe blockchain. Any modifications to the multimedia content require onlyupdating the signature of the auxiliary data, which is securely recordedon the blockchain. Thus, the proposed approach enables verification ofintegrity of redacted multimedia content without compromising thecontent privacy requirements.

In today's era of unreliable news, the easy availability of multimediamanipulation tools has made it difficult to trust what we see (image orvideo) or hear (audio). However, multimedia data (e.g., audio/videorecordings) are admissible as evidence in courts and are often portrayedby the media as the ultimate “truth” of what happened. While significantadvancements have been made in the field of multimedia forensics todetect altered content, these techniques are mostly passive because thecontent recipient attempts to verify the integrity of multimedia datawithout any inputs from the content creator. In many scenarios (e.g.,citizen journalism, law enforcement), the content creator does have astrong incentive to establish the provenance and integrity of themultimedia data created and released by him.

Though active content authentication solutions such as watermarking anddigital signatures have been proposed, they do not provide the creatorof multimedia content with the ability to prove to a future recipientthe following claims about the content: (i) ownership, (ii) device usedto create the content, (iii) time of creation, and (iv) either thecontent has not been modified after creation or an immutable log ofmodifications made to the content after creation. These requirements canbe met by enabling the content owner to make an irrefutable commitmentabout the multimedia content at the time of creation so that a therecipient can verify these details at a later point in time.

Blockchain is a peer-to-peer distributed ledger that immutably records asequence of transactions without the need for any centralized or trustedentities. While blockchain has already been successfully applied incryptocurrencies such as Bitcoin, the underlying technology can be usedto create a tamper-proof audit trail in many applications. When combinedwith smart contracts o chaincodes, blockchain is a natural solution forstoring the multimedia content creation record and immutably trackingall permissible changes after content creation. Note that commitments onthe blockchain can be performed directly by the content creator orthrough a third-party service provider. While ownership of the contentcan be established through biometric authentication of the creator, thedevice itself can be authenticated through its unique fingerprint (e.g.,photo response non-uniformity (PRNU) of a camera or microphoneimperfections). Solutions are also available for trusted time-stampingof multimedia content using blockchain. Therefore, the presentapplication focuses only the content authentication problem, andspecifically on challenges in proving authenticity after revisions aremade to the media after its creation.

The main limitation of blockchain-based approach is that the contentcreator is required to commit to a tamper-proof signature of the contentat the time of its creation. Any further modifications to the contentwill surely invalidate this signature. In real-world use cases, thecreator may have valid reasons to alter the content before distribution.For example, a bodycam video captured by law enforcement is used toprove innocence of the officer and a true description of the event.However, the privacy of the subjects in the video is important. Hence,the contents are sometimes redacted before they are released to thepublic. One would expect that the edited released video continues tofaithfully depict the true event while protecting personally sensitiveinformation of its subjects. Similar requirements are also felt in legaldocuments and scene-of-crime pictures. One possible solution is toemploy redactable or sanitizable signature schemes to generate theinitial commitment. The key limitation of such schemes is the need for atrusted third-party ‘censor’ or ‘sanitizer’, who performs the redactionon behalf of the content creator. Secondly, this approach also assumes aperfect communication protocol between the creator and the censor.Sanitizable signature schemes rely on this feature to prevent thecreator from making undetectable modifications. Moreover, since theredacted segments may have a low entropy or randomness, the publishedcommitment should not leak any information that enables the receiver tounwrap the redacted segments.

The present application describes a novel blockchain-based solution formultimedia integrity verification that overcomes all of theabove-mentioned limitations. The primary contribution of this work is asanitizable signature method that utilizes the properties of blockchain,chameleon hash functions, and Merkle trees to efficiently sign the givenmultimedia content, transparently update the signature upon contentmodification, and verify the integrity of the released content. We alsopresent a theoretical analysis of the security properties andcomputational complexity of the proposed solution.

FIG. 1A illustrates a logic network diagram of a system 100 for securelystoring source media files to a blockchain, according to exampleembodiments. Referring to FIG. 1A, the system 100 includes a filecreator 108, who is a user who creates or captures a source file 116with a source device 112. The source device 112 may be a computer of anytype including a mobile computer, a desktop computer, a server, asmartphone, or a wearable computer. Such a computer 112 may or may notinclude a camera, a microphone, speakers, or a display. The sourcedevice 112 may additionally or alternately include a picture camera, avideo camera, or an audio recorder. The source file 116 may contain anycombination of text (as a document), video, audio, or graphics 114. Oneor more of text, video, audio, or graphics 114 may not be present in thesource file 116. The source device 112 can make use of deviceauthentication 144 and the authenticated source device 146 can be storedon the blockchain network 104.

The present application makes use of biometric authentication 148 inorder to ensure provenance of both the file creator 108A and the sourcedevice 112 used to create or capture the source file 116. Provenance, inthe context of the present application, is the history of ownership backto the origin of the source file 116. Biometric authentication 148 isused to create a blockchain transaction that stores an authenticatedfile creator and source device signature 150A to a shared ledger of ablockchain network 104. The blockchain network 104 may be either apublic or a permissioned blockchain network 104. The only differencelies in how the transaction is approved by the relevant stakeholders. Ina permissioned blockchain this can be handled via smart contracts andendorsement policies. In a public blockchain, multi-signatures can beemployed to obtain “pre-approval” before the miners commit thetransaction to the blockchain.

Once the source file 116 has been created or captured by the filecreator 108A, the source file 116 is segmented by a segmentationfunction 120 into a plurality of source file segments 122A. Variousforms of existing software and software applications may be used tosegment the source file 116. In one embodiment, the source file segments122A are of equal size. In another embodiment, some source file segments122A are of a first size while other source file segments 122A are of adifferent second size. In another embodiment, source file segments 122Aare of a variable size. The segmentation function 120 produces N sourcefile segments 122A, where N is the number of source file segments 122A.

Following segmentation 120, an auxiliary data generation function 124generates N auxiliary data segments 125. Therefore, the number N ofauxiliary data segments 125 is equal to the number N of source filesegments 122A. Auxiliary data is a random string of data that isgenerated independent of the source file 116. This random string of datais then segmented into the auxiliary data segments 125. At this point,there are N source file segments 122A and N auxiliary data segments 125.Alternately, one may generate N random (shorter) strings individually.

The present application utilizes both a chameleon hashing function 128and a cryptographic hash function 136 to process the source filesegments 122A and the auxiliary data segments 125. Chameleon hashfunctions are randomized collision-resistant hash functions with theadditional property that given a trapdoor, one can efficiently generatecollisions. More specifically, each function in the family is associatedwith a pair of public and private (trapdoor) keys with the followingproperties (i) anyone who knows the public key can compute theassociated hash function, (ii) for those who do not know the trapdoorthe function is collision resistant in the usual sense, and (iii) theholder of the trapdoor information can easily find collisions for everyinput. A cryptographic hash function is a mathematical algorithm thatmaps data of arbitrary size to a bit string of a fixed size (a hash) andis designed to be a one-way function, that is, a function which isinfeasible to invert. The only way to recreate the input data from anideal cryptographic hash function's output is to attempt a brute-forcesearch of possible inputs to see if they produce a match, or use arainbow table of matched hashes.

The chameleon hashing function 128 converts source file segments 122A(nodes M1, M2, M3, and M4 of FIG. 1B) and auxiliary data segments 125(nodes A1, A2, A3, and A4 of FIG. 1B) as inputs into chameleon hash leafnodes (nodes V4, V5, V6, and V7 of FIG. 1B).

A chameleon hash is defined by the triplet: (Gen; CH; CH⁻¹), where Genis a key generation algorithm that generates a key pair (HK; TD), withHK being the hashing (public) key and TD being the trapdoor (secret) key168 that is used for finding collisions. The public key HK defines achameleon hash function CH_(HK)(,), which on input a message m and arandom string a (previously referred to as auxiliary data), generates ahash value CH_(HK)(m, a) that satisfies the following properties.

-   -   Collision Resistance: Given only CH_(HK)(,), there is no        efficient algorithm to find pairs (m1, a1) and (m2, a2) where        (m1, a1) is not equal to (m2, a2) such that CH_(HK)(m1,        a1)=CH_(HK)(m2, a2), except with negligible probability.    -   Trapdoor collisions: There is an efficient algorithm (CH⁻¹) that        on input the secret key TD, any pair (m1, a1) and any additional        message m2, outputs a value a2 such that CH_(HK)(m1,        a1)=CH_(HK)(m2, a2).    -   Uniformity: From seeing CH_(HK)(m, a), where a is chosen        uniformly at random, nothing is learned about the message m.

The cryptographic hash function 136 converts auxiliary data segments 125(nodes A1, A2, A3, and A4 of FIG. 1B) into cryptographic hash leaf nodes(nodes U4, U5, U6, and U7 of FIG. 1B).

The Merkle Tree signature function 132 receives the chameleon hash leafnodes (nodes V4, V5, V6, and V7 of FIG. 1B) and generates leaf nodes V2and V3 and root node V1 as hashes. The Merkle Tree signature function140 receives the cryptographic hash leaf nodes (nodes U4, U5, U6, and U7of FIG. 1B) and generates leaf nodes U2 and U3 and root node U1 ashashes. Root node V1 is a chameleon hash signature 134 and root node U1is an auxiliary data hash signature 142. Both signatures 134, 140 arestored to the shared ledger of blockchain network 104 through blockchaintransactions. At this point, the signatures corresponding to the sourcefile 116 and authentication results for the file creator 108A and sourcedevice 112 are stored to the immutable shared ledger.

System 100 is a sanitizable signature system that allows a file creator108A to sign the file or multimedia content at the time of its creationand record this initial signature on a blockchain. The blockchain shouldmaintain an immutable log of the segments that were modified. At anygiven point in time (after content creation), a recipient who receivesthe content from the file creator 108A should be able to verify theintegrity of the received content, i.e., identify which segments havebeen modified and ensure that the remaining segments have not beenaltered by the file creator 108A.

FIG. 1B illustrates sanitizable signature generation 150 for a file in ablockchain, according to example embodiments. Referring to FIG. 1B, thesignatures 150 are based on a source file M. The source file M isdivided into source file segments 122A, identified as source filesegments M1, M2, M3, and M4. There may be any number of source filesegments 122A in a source file 116, although four such segments 122A areshown in FIG. 1B for simplicity.

Associated with each of the source file segments 122A is an auxiliarydata segment 125, identified as auxiliary data segments A1, A2, A3, andA4. A chameleon hash Merkle tree 152 is created from the source filesegments 122A and the auxiliary data segments 125. In a binary Merkletree, every leaf node is labeled with a cryptographic hash of the inputdata blocks and every non-leaf node is labelled with the cryptographichash of the labels of its two child nodes. In the present application,the input data blocks are the chameleon hashes of the individualsegments.

Leaf node V4 is created from source file segment M1 and auxiliary datasegment A1. Leaf node V5 is created from source file segment M2 andauxiliary data segment A2. Leaf node V6 is created from source filesegment M3 and auxiliary data segment A3. Leaf node V7 is created fromsource file segment M4 and auxiliary data segment A4. Leaf node V2 iscreated from hashes of leaf nodes V4 and V5. Leaf node V3 is createdfrom hashes of leaf nodes V6 and V7. Finally, a root node V1 is createdfrom hashes of leaf nodes V2 and V3. The root node V1 is chameleon hashroot node 134, which is the signature that is stored to the sharedledger of the blockchain network 104 for the source file.

An auxiliary data Merkle tree 156 is created from the auxiliary datasegments 125. Leaf node U4 is created from auxiliary data segment A1.Leaf node U5 is created from auxiliary data segment A2. Leaf node U6 iscreated from auxiliary data segment A3. Leaf node U7 is created fromauxiliary data segment A4. Leaf node U2 is created from hashes of leafnodes U4 and U5. Leaf node U3 is created from hashes of leaf nodes U6and U7. Finally, root node U1 is created from hashes of leaf nodes U2and U3. The root node U1 is auxiliary data root node 142A, which is thesignature that is stored to the shared ledger of the blockchain network104 for the auxiliary data file. Both the content (i.e. corresponding tothe source file 116) and auxiliary data signatures are broadcast to theblockchain nodes, which verify both the signatures before recording (U1,V1) on the shared ledger, along with metadata about the content.

FIG. 1C illustrates a logic network diagram of a system 160 for securelyredacting source media files to a blockchain, according to exampleembodiments. Referring to FIG. 1C, the system 160 includes a redactedfile creator 108B, who is a user who redacts or otherwise modifies thesource file 116. In one embodiment, the redacted file creator 108B is adifferent individual than the file creator 108A. In another embodiment,the redacted file creator 108B is a same individual as the file creator108A.

The present application makes use of biometric authentication 148 inorder to ensure provenance of the redacted file creator 108B.Provenance, in the context of the present application, is the history ofownership back to the origin of the source file 116. Biometricauthentication 148 is used to create a blockchain transaction thatstores an authenticated redacted file creator signature 150B to theshared ledger of the blockchain network 104. Once authenticated, theredacted file creator 108B redacts/modifies a subset of segments in thecontent, and updates the initial signature on the blockchain. Onecritical requirement is content privacy, which implies that an adversaryhaving access to the redacted content and logs available on theblockchain should not be able to reconstruct the original data that wasredacted by the redacted file creator 108B.

After the source file 116 has been created or captured by the filecreator 108A, the redacted file creator 108B utilizes redaction software164 to convert one or more source file segments 122B into redacted filesegments 122B.

A collision finding function 172 uses the trapdoor key 168 to convertthe redacted file segments 122B and auxiliary data segments 125 intomodified auxiliary data 174. Finally, a smart contract or chaincode forauxiliary data signature update 176 converts the modified auxiliary data174 into a modified auxiliary data signature and redacted segmentsidentifiers (IDs) 178. The modified auxiliary data signature andredacted segments identifiers (IDs) 178 is included in a blockchaintransaction, which following conventional transaction endorsement iscommitted to the shared ledger. At this point, the blockchain includesauthentications for the file creator 108A, source device 112, andredacted file creator 108B as well as the (original) chameleon hashsignature 134, auxiliary data hash signature 142, the modified auxiliarydata signature 178, and redacted segments IDs 178.

FIG. 1D illustrates sanitizable signature redaction 180 for a file in ablockchain, according to example embodiments. Referring to FIG. 1D, thesignatures 180 are based on a redacted source file M. The source file Mis divided into redacted source file segments 122B, identified asredacted source file segments M1, M2, M3′, and M4. Redacted source filesegment M3′ represents a redacted source file segment. There may be anynumber of redacted source file segments 122B in a redacted source file,although four such segments 122B are shown in FIG. 1D for simplicity.

Associated with each of the redacted source file segments 122B isauxiliary data segments 125, identified as auxiliary data segments A1,A2, A3′, and A4. Auxiliary data segment A3′ is modified auxiliary data174. In the case of redaction, a new chameleon hash Merkle tree 152 andchameleon hash root node 134 are not created; all that is needed is amodified auxiliary data Merkle tree 182 and a modified auxiliary datahash root node 142B.

The modified auxiliary data Merkle tree 182 is created from theauxiliary data segments 125. And the modified auxiliary data 174. Leafnode U4 is created from auxiliary data segment A1. Leaf node U5 iscreated from auxiliary data segment A2. Leaf node U6′ is created frommodified auxiliary data segment A3′. Leaf node U7 is created fromauxiliary data segment A4. Leaf node U2 is created from leaf nodes U4and U5. Leaf node U3 is created from leaf nodes U6′ and U7. Finally,root node U1 is created from leaf nodes U2 and U3. The root node U1 is amodified auxiliary hash data root node 142B, which is the signature thatis stored to the shared ledger of the blockchain network 104 for theredacted data. Modified auxiliary hash data root node 142B may becreated from leaf nodes U2, U6′, and U7 184, which are represented inFIG. 1D as underlines to denote their special use when constructing rootnode U1.

FIG. 1E illustrates a logic network diagram of a system 185 for securelyverifying source media files from a blockchain, according to exampleembodiments. Referring to FIG. 1E, the system 185 includes a fileverifier 108C, who is a user who verifies either the source file 116 orthe redacted source file. In one embodiment, the file verifier 108C is adifferent individual than the file creator 108A or redacted file creator108B. In another embodiment, file verifier 108C is a same individual asone or both of the file creator 108A or the redacted file creator 108B.

The present application makes use of biometric authentication 148 inorder to ensure provenance of principally the file creator 108A, andoptionally the file verifier 108C to track the recipients of the file.It is important for the file verifier 108C to verify the identity of thesender (i.e. a request for biometric identification of the file creator108A) to ensure the file was indeed created by the sender. Biometricauthentication 148 is used to create a blockchain transaction thatstores an authenticated file verifier signature 150C to the sharedledger of the blockchain network 104.

Depending on whether the source file 116 or redacted source file isbeing verified, the input to the chameleon hash function 128 may differ.If the source file 116 is being verified, the inputs to the chameleonhashing function 128 are the source file segments 122A and the auxiliarydata segments 125. If the redacted source file is being verified, theinputs to the chameleon hashing function 128 are the redacted filesegments 122B and the modified auxiliary data 174. Similarly, if thesource file 116 is being verified, the input to the cryptographichashing function 136 is the auxiliary data segments 125. If the redactedsource file is being verified, the input to the cryptographic hashingfunction 136 is the modified auxiliary data 174.

The Merkle tree signature function 132 produces a chameleon hashsignature 132 to a smart contract for verification 190, and the Merkletree signature function 140 produces an auxiliary data hash signature142 to the smart contract for verification 190. The smart contract forverification, after receiving the chameleon hash signature 134 and theauxiliary data hash signature 142, retrieves the stored signatures fromthe shared ledger and compares the newly calculated chameleon hashsignature 134 and the auxiliary data hash signature 142 to the storedsignatures.

If the signatures match, then the integrity of the source file 116 orredacted source file has been verified, and the smart contract forverification 190 provides a verification successful notification 192 andan identifier for the redacted segments 194 (if a redacted file is beingverified). If the signatures do not match, this may be an indication oftampering or other form of fraud detection and typically an appropriatenotification would be provided to the file verifier 108C and/or a systemadministrator.

FIG. 2A illustrates a blockchain architecture configuration 200,according to example embodiments. Referring to FIG. 2A, the blockchainarchitecture 200 may include certain blockchain elements, for example, agroup of blockchain nodes 202. The blockchain nodes 202 may include oneor more nodes 204-210 (these four nodes are depicted by example only).These nodes participate in a number of activities, such as blockchaintransaction addition and validation process (consensus). One or more ofthe blockchain nodes 204-210 may endorse transactions based onendorsement policy and may provide an ordering service for allblockchain nodes in the architecture 200. A blockchain node may initiatea blockchain authentication and seek to write to a blockchain immutableledger stored in blockchain layer 216, a copy of which may also bestored on the underpinning physical infrastructure 214. The blockchainconfiguration may include one or more applications 224 which are linkedto application programming interfaces (APIs) 222 to access and executestored program/application code 220 (e.g., chaincode, smart contracts,etc.) which can be created according to a customized configurationsought by participants and can maintain their own state, control theirown assets, and receive external information. This can be deployed as atransaction and installed, via appending to the distributed ledger, onall blockchain nodes 204-210.

The blockchain base or platform 212 may include various layers ofblockchain data, services (e.g., cryptographic trust services, virtualexecution environment, etc.), and underpinning physical computerinfrastructure that may be used to receive and store new transactionsand provide access to auditors which are seeking to access data entries.The blockchain layer 216 may expose an interface that provides access tothe virtual execution environment necessary to process the program codeand engage the physical infrastructure 214. Cryptographic trust services218 may be used to verify transactions such as asset exchangetransactions and keep information private.

The blockchain architecture configuration of FIG. 2A may process andexecute program/application code 220 via one or more interfaces exposed,and services provided, by blockchain platform 212. The code 220 maycontrol blockchain assets. For example, the code 220 can store andtransfer data, and may be executed by nodes 204-210 in the form of asmart contract and associated chaincode with conditions or other codeelements subject to its execution. As a non-limiting example, smartcontracts may be created to execute reminders, updates, and/or othernotifications subject to the changes, updates, etc. The smart contractscan themselves be used to identify rules associated with authorizationand access requirements and usage of the ledger. For example, theinformation 226 may include various verification request transactions.Verification request transactions 226 may be processed by one or moreprocessing entities (e.g., virtual machines) included in the blockchainlayer 216. The result 228 may include a source file and data signatures.The physical infrastructure 214 may be utilized to retrieve any of thedata or information described herein.

Within chaincode, a smart contract may be created via a high-levelapplication and programming language, and then written to a block in theblockchain. The smart contract may include executable code which isregistered, stored, and/or replicated with a blockchain (e.g.,distributed network of blockchain peers). A transaction is an executionof the smart contract code which can be performed in response toconditions associated with the smart contract being satisfied. Theexecuting of the smart contract may trigger a trusted modification(s) toa state of a digital blockchain ledger. The modification(s) to theblockchain ledger caused by the smart contract execution may beautomatically replicated throughout the distributed network ofblockchain peers through one or more consensus protocols.

The smart contract may write data to the blockchain in the format ofkey-value pairs. Furthermore, the smart contract code can read thevalues stored in a blockchain and use them in application operations.The smart contract code can write the output of various logic operationsinto the blockchain. The code may be used to create a temporary datastructure in a virtual machine or other computing platform. Data writtento the blockchain can be public and/or can be encrypted and maintainedas private. The temporary data that is used/generated by the smartcontract is held in memory by the supplied execution environment, thendeleted once the data needed for the blockchain is identified.

A chaincode may include the code interpretation of a smart contract,with additional features. As described herein, the chaincode may beprogram code deployed on a computing network, where it is executed andvalidated by chain validators together during a consensus process. Thechaincode receives a hash and retrieves from the blockchain a hashassociated with the data template created by use of a previously storedfeature extractor. If the hashes of the hash identifier and the hashcreated from the stored identifier template data match, then thechaincode sends an authorization key to the requested service. Thechaincode may write to the blockchain data associated with thecryptographic details. In FIG. 2A, a blockchain platform 212 may receivea blockchain transaction 226 to verify the integrity of a file stored onthe blockchain. One function may be to request source file and auxiliarydata signatures 228, which may be provided to one or more of the nodes204-210.

FIG. 2B illustrates an example of a transactional flow 250 between nodesof the blockchain in accordance with an example embodiment. Referring toFIG. 2B, the transaction flow may include a transaction proposal 291sent by an application client node 260 to an endorsing peer node 281.The endorsing peer 281 may verify the client signature and execute achaincode function to initiate the transaction. The output may includethe chaincode results, a set of key/value versions that were read in thechaincode (read set), and the set of keys/values that were written inchaincode (write set). The proposal response 292 is sent back to theclient 260 along with an endorsement signature, if approved. The client260 assembles the endorsements into a transaction payload 293 andbroadcasts it to an ordering service node 284. The ordering service node284 then delivers ordered transactions as blocks to all peers 281-283 ona channel. Before committal to the blockchain, each peer 281-283 mayvalidate the transaction. For example, the peers may check theendorsement policy to ensure that the correct allotment of the specifiedpeers have signed the results and authenticated the signatures againstthe transaction payload 293.

Referring again to FIG. 2B, the client node 260 initiates thetransaction 291 by constructing and sending a request to the peer node281, which is an endorser. The client 260 may include an applicationleveraging a supported software development kit (SDK), such as NODE,JAVA, PYTHON, and the like, which utilizes an available API to generatea transaction proposal. The proposal is a request to invoke a chaincodefunction so that data can be read and/or written to the ledger (i.e.,write new key value pairs for the assets). The SDK may serve as a shimto package the transaction proposal into a properly architected format(e.g., protocol buffer over a remote procedure call (RPC)) and take theclient's cryptographic credentials to produce a unique signature for thetransaction proposal.

In response, the endorsing peer node 281 may verify (a) that thetransaction proposal is well formed, (b) the transaction has not beensubmitted already in the past (replay-attack protection), (c) thesignature is valid, and (d) that the submitter (client 260, in theexample) is properly authorized to perform the proposed operation onthat channel. The endorsing peer node 281 may take the transactionproposal inputs as arguments to the invoked chaincode function. Thechaincode is then executed against a current state database to producetransaction results including a response value, read set, and write set.However, no updates are made to the ledger at this point. In 292, theset of values, along with the endorsing peer node's 281 signature ispassed back as a proposal response 292 to the SDK of the client 260which parses the payload for the application to consume.

In response, the application of the client 260 inspects/verifies theendorsing peers signatures and compares the proposal responses todetermine if the proposal response is the same. If the chaincode onlyqueried the ledger, the application would inspect the query response andwould typically not submit the transaction to the ordering node service284. If the client application intends to submit the transaction to theordering node service 284 to update the ledger, the applicationdetermines if the specified endorsement policy has been fulfilled beforesubmitting (i.e., did all peer nodes necessary for the transactionendorse the transaction). Here, the client may include only one ofmultiple parties to the transaction. In this case, each client may havetheir own endorsing node, and each endorsing node will need to endorsethe transaction. The architecture is such that even if an applicationselects not to inspect responses or otherwise forwards an unendorsedtransaction, the endorsement policy will still be enforced by peers andupheld at the commit validation phase.

After successful inspection, in step 293 the client 260 assemblesendorsements into a transaction and broadcasts the transaction proposaland response within a transaction message to the ordering node 284. Thetransaction may contain the read/write sets, the endorsing peerssignatures and a channel ID. The ordering node 284 does not need toinspect the entire content of a transaction in order to perform itsoperation, instead the ordering node 284 may simply receive transactionsfrom all channels in the network, order them chronologically by channel,and create blocks of transactions per channel.

The blocks of the transaction are delivered from the ordering node 284to all peer nodes 281-283 on the channel. The transactions 294 withinthe block are validated to ensure any endorsement policy is fulfilledand to ensure that there have been no changes to ledger state for readset variables since the read set was generated by the transactionexecution. Transactions in the block are tagged as being valid orinvalid. Furthermore, in step 295 each peer node 281-283 appends theblock to the channel's chain, and for each valid transaction the writesets are committed to current state database. An event is emitted, tonotify the client application that the transaction (invocation) has beenimmutably appended to the chain, as well as to notify whether thetransaction was validated or invalidated.

FIG. 3 illustrates an example of a permissioned blockchain network 300,which features a distributed, decentralized peer-to-peer architecture,and a certificate authority 318 managing user roles and permissions. Inthis example, the blockchain user 302 may submit a transaction to thepermissioned blockchain network 310. In this example, the transactioncan be a deploy, invoke, or query, and may be issued through aclient-side application leveraging an SDK, directly through a REST API,or the like. Trusted business networks may provide access to regulatorsystems 314, such as auditors (the Securities and Exchange Commission ina U.S. equities market, for example). Meanwhile, a blockchain networkoperator system of nodes 308 manage member permissions, such asenrolling the regulator system 314 as an “auditor” and the blockchainuser 302 as a “client”. An auditor could be restricted only to queryingthe ledger whereas a client could be authorized to deploy, invoke, andquery certain types of chaincode.

A blockchain developer system 316 writes chaincode and client-sideapplications. The blockchain developer system 316 can deploy chaincodedirectly to the network through a REST interface. To include credentialsfrom a traditional data source 330 in chaincode, the developer system316 could use an out-of-band connection to access the data. In thisexample, the blockchain user 302 connects to the network through a peernode 312. Before proceeding with any transactions, the peer node 312retrieves the user's enrollment and transaction certificates from thecertificate authority 318. In some cases, blockchain users must possessthese digital certificates in order to transact on the permissionedblockchain network 310. Meanwhile, a user attempting to drive chaincodemay be required to verify their credentials on the traditional datasource 330. To confirm the user's authorization, chaincode can use anout-of-band connection to this data through a traditional processingplatform 320.

FIG. 4A illustrates a system messaging diagram for performing sourcefile signature generation 400, according to example embodiments.Referring to FIG. 4A, the system messaging diagram 400 includes a filecreator 410, a signature generation function 420, and a blockchainnetwork 430. The file creator 410 has responsibility for creating orcapturing a source file 116, as explained with reference to FIGS. 1A and1B.

The file creator 410 creates or captures a source file 412 with a sourcedevice 112. The file creator 410 then biometrically authenticates 414Ahis/her identity and the identity of the source device 112, and submitsa file creator and source device authentication transaction 416 to theblockchain network 430. In response, the blockchain network 430 endorsesthe transaction 422A and stores the authentications to the shared ledger424 of the blockchain network 430.

The file creator 410 next submits the source file 418 to the signaturegeneration function 420. The signature generation function 420 inresponse segments the source file 426 as previously described withreference to FIGS. 1A and 1B, and performs a chameleon hash 428 andcryptographic hash on the source file segments and auxiliary datasegments, and processes Merkle trees 432. Processing the Merkle trees432 produces a source file signature and an auxiliary data signature,which are included as a blockchain transaction 434 to the blockchainnetwork 430. In response, the blockchain network 430 endorses thetransaction 422B and stores both signatures to the shared ledger 436 ofthe blockchain network 430.

The signature generation function 420 then transfers the auxiliary data438 and a trapdoor key (used for the chameleon hash 428) back to thefile creator 410, who stores both 442. At this point, both the sourcefile and auxiliary data signatures as well as file creator and sourcedevice authentications are stored to a shared ledger of the blockchainnetwork 430, and the file creator 410 stores the original source file,auxiliary data 438, and the trapdoor key 440.

FIG. 4B illustrates a system messaging diagram for performing sourcefile signature redaction 445, according to example embodiments.Referring to FIG. 4B, the system messaging diagram 445 includes aredacted file creator 450, a signature update function 452, and ablockchain network 430.

The redacted file creator 450 determines redacted source file segments454 by redacting or modifying the source file. The redacted file creator450 then biometrically authenticates 414B his/her identity and submits aredacted file creator authentication transaction 456 to the blockchainnetwork 430. In response, the blockchain network 430 endorses thetransaction 422C and stores the authentications to the shared ledger 458of the blockchain network 430.

The redacted file creator 450 next submits redacted source file segments460 to the signature update function 452, along with the storedauxiliary data 438 and the trapdoor key 440. The signature updatefunction 452 in response generates modified auxiliary data 462 aspreviously described with reference to FIGS. 1C and 1D. The signatureupdate function 452 produces modified auxiliary data 462, and computes amodified auxiliary data signature 463, and provides a modified auxiliarydata signature blockchain transaction 464 to the blockchain network 430.In response, the blockchain network 430 endorses the transaction 422Dand stores modified segments identification 466 and a modified auxiliarydata signature 468 to the shared ledger of the blockchain network 430.

FIG. 4C illustrates a system messaging diagram for performing signatureverification 470, according to example embodiments. Referring to FIG.4C, the system messaging diagram 470 includes a file verifier 472, asignature verification function 474, and a blockchain network 430.

The file verifier 472 verifies the integrity of a source file signatureor a redacted file signature previously stored to the blockchain network430. The file verifier 472 receives source file, redacted file, andauxiliary file 476. The file verifier 472 biometrically authenticates414C his/her identity, and submits a file verifier authenticationtransaction 478 to the blockchain network 430. In response, theblockchain network 430 endorses the transaction 422E and stores theauthentications to the shared ledger 480 of the blockchain network 430.

The file verifier 472 next submits the source file or redacted filesegments 482 and auxiliary data or modified auxiliary data 484 to thesignature verification function 474. The signature verification function474 in response performs a chameleon hash 428 on the source filesegments or redacted file segments 482 and auxiliary data or modifiedauxiliary data 484, performs a cryptographic hash on the auxiliary dataor modified auxiliary data 484, and processes Merkle trees 432.Processing the Merkle trees 432 produces a source file signature and anauxiliary data signature, which are included in a verify signatures 488blockchain transaction 486 to the blockchain network 430. In response,the blockchain network 430 endorses the transaction 422F and a smartcontract or chaincode of the blockchain network 430 verifies thesignatures in the transaction 486 with the stored signatures on theblockchain.

If the signatures match, the blockchain network 430 provides asignatures verified notification 490 to the file verifier 472.

FIG. 5A illustrates a flow diagram 500 of an example method of creatingsource file signatures in a blockchain, according to exampleembodiments. Referring to FIG. 5A, the method 500 may include one ormore of the following steps.

At block 502, a file creator 410 creates a source file with a sourcedevice. The source file may include text, video, audio, and/or graphics.

At block 504, the file creator 410 and source device are biometricallyauthenticated, and the authentications are stored to a blockchain.

At block 506, the source file is segmented into any number of segments.

At block 508, auxiliary data is created that corresponds to the sourcefile segments.

At block 510, a chameleon hash is created from the source file segmentsand the auxiliary data.

At block 512, a cryptographic hash is created from the auxiliary data.

At block 514, signatures resulting from the chameleon hash and thecryptographic hash are stored to a shared ledger of the blockchain.

FIG. 5B illustrates a flow diagram 520 of an example method of creatinga redacted source file signature in a blockchain, according to exampleembodiments. Referring to FIG. 5B, the method 520 may include one ormore of the following steps.

At block 522, a redacted file creator 450 creates a redacted sourcefile, which removes or modifies one or more portions of the source file.The redacted source file may include text, video, audio, and/orgraphics.

At block 524, the redacted file creator 450 is biometricallyauthenticated, and the authentications are stored to the blockchain.

At block 526, modified auxiliary data based on the redacted source fileis generated.

At block 528, a modified auxiliary data signature is computed thatcorresponds to the modified auxiliary data.

At block 530, the modified auxiliary data signature is stored to ashared ledger of the blockchain.

FIG. 5C illustrates a flow diagram 540 of an example method of verifyingsource and redacted file signatures in a blockchain, according toexample embodiments. Referring to FIG. 5C, the method 540 may includeone or more of the following steps.

At block 542, a file verifier 472 receives a source file, redactedsegments of the source file, and auxiliary data. The source file andredacted source file may include text, video, audio, and/or graphics.

At block 544, the file verifier 472 are biometrically authenticated, andthe authentications are stored to the blockchain.

At block 546, a chameleon hash is created from either the source filesegments or redacted file segments, and the auxiliary data.

At block 548, the file verifier 472 retrieves stored signatures for thesource file or redacted source file and compares the retrievedsignatures to the calculated source file hash or redacted source filehash.

At block 550, the file verifier 472 is notified if the stored signaturesmatch the calculated signatures (hashes).

FIG. 5D illustrates a flow diagram 560 of an example method of redactinga document associated with a blockchain transaction, according toexample embodiments. Referring to FIG. 5B, the method 560 may includeone or more of the following steps.

At block 562, the method may also include identifying a blockchaintransaction. The transaction may include content to be redacted. Whenredacting a transaction, the data that was originally identified in thetransaction may be hidden or blocked from view in the actual committedblockchain transaction. For example, once a transaction is identified asrequiring redaction, the transaction may still exist in a block topreserve immutability of that transaction, however, the transaction maybe otherwise inaccessible and cannot be accessed or viewed by users. Forexample, one approach may include placing a contract in a genesis blockof the blockchain with code indicating to record redacted transactions.Additionally, by sending a new transaction to the redaction contractidentifying a particular blockchain transaction to be redacted, the newtransaction may be recorded and a redaction procedure may identify the“improper transaction” as the transaction to be redacted on theblockchain.

At block 564, the method includes pre-processing the blockchaintransaction to identify whether content of the blockchain transaction isapproved by one or more devices on a peer network associated with theblockchain.

At block 566, the method includes approving content by one or moredevices. If a transaction contains unexpected content, thepre-processing will identify this content and it will not be finalizedor stored in the blockchain. As such, miner devices have their ownfilter for approving content (or not) and a consensus may be reachedregarding the acceptance of content of a transaction.

At block 568, the method includes processing the identified content bythe one or more devices, in response to approving the content by the oneor more devices.

At block 570, the method includes storing the blockchain transaction onthe blockchain. In this example, a pre-processing operation confirms thecontent of the transaction is recognizable or expected by potentialminer devices on the peer network prior to committing a transaction thatshould not be permitted.

FIG. 6A illustrates an example system 600 that includes a physicalinfrastructure 610 configured to perform various operations according toexample embodiments. Referring to FIG. 6A, the physical infrastructure610 includes a module 612 and a module 614. The module 614 includes ablockchain 620 and a smart contract 630 (which may reside on theblockchain 620), that may execute any of the operational steps 608 (inmodule 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6B illustrates an example system 640 configured to perform variousoperations according to example embodiments. Referring to FIG. 6B, thesystem 640 includes a module 612 and a module 614. The module 614includes a blockchain 620 and a smart contract 630 (which may reside onthe blockchain 620), that may execute any of the operational steps 608(in module 612) included in any of the example embodiments. Thesteps/operations 608 may include one or more of the embodimentsdescribed or depicted and may represent output or written informationthat is written or read from one or more smart contracts 630 and/orblockchains 620. The physical infrastructure 610, the module 612, andthe module 614 may include one or more computers, servers, processors,memories, and/or wireless communication devices. Further, the module 612and the module 614 may be a same module.

FIG. 6C illustrates an example smart contract configuration amongcontracting parties and a mediating server configured to enforce thesmart contract terms on the blockchain according to example embodiments.Referring to FIG. 6C, the configuration 650 may represent acommunication session, an asset transfer session or a process orprocedure that is driven by a smart contract 630 which explicitlyidentifies one or more user devices 652 and/or 656. The execution,operations and results of the smart contract execution may be managed bya server 654. Content of the smart contract 630 may require digitalsignatures by one or more of the entities 652 and 656 which are partiesto the smart contract transaction. The results of the smart contractexecution may be written to a blockchain 620 as a blockchaintransaction. The smart contract 630 resides on the blockchain 620 whichmay reside on one or more computers, servers, processors, memories,and/or wireless communication devices.

FIG. 6D illustrates a system 660 including a blockchain, according toexample embodiments. Referring to the example of FIG. 6D, an applicationprogramming interface (API) gateway 662 provides a common interface foraccessing blockchain logic (e.g., smart contract 630 or other chaincode)and data (e.g., distributed ledger, etc.). In this example, the APIgateway 662 is a common interface for performing transactions (invoke,queries, etc.) on the blockchain by connecting one or more entities 652and 656 to a blockchain peer (i.e., server 654). Here, the server 654 isa blockchain network peer component that holds a copy of the world stateand a distributed ledger allowing clients 652 and 656 to query data onthe world state as well as submit transactions into the blockchainnetwork where, depending on the smart contract 630 and endorsementpolicy, endorsing peers will run the smart contracts 630.

The above embodiments may be implemented in hardware, in a computerprogram executed by a processor, in firmware, or in a combination of theabove. A computer program may be embodied on a computer readable medium,such as a storage medium. For example, a computer program may reside inrandom access memory (“RAM”), flash memory, read-only memory (“ROM”),erasable programmable read-only memory (“EPROM”), electrically erasableprogrammable read-only memory (“EEPROM”), registers, hard disk, aremovable disk, a compact disk read-only memory (“CD-ROM”), or any otherform of storage medium known in the art.

An exemplary storage medium may be coupled to the processor such thatthe processor may read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anapplication specific integrated circuit (“ASIC”). In the alternative,the processor and the storage medium may reside as discrete components.

FIG. 7A illustrates a process 700 of a new block being added to adistributed ledger 730, according to example embodiments, and FIG. 7Billustrates contents of a block structure 750 for blockchain, accordingto example embodiments. Referring to FIG. 7A, clients (not shown) maysubmit transactions to blockchain nodes 721, 722, and/or 723. Clientsmay be instructions received from any source to enact activity on theblockchain 730. As an example, clients may be applications that act onbehalf of a requester, such as a device, person or entity to proposetransactions for the blockchain. The plurality of blockchain peers(e.g., blockchain nodes 721, 722, and 723) may maintain a state of theblockchain network and a copy of the distributed ledger 730. Differenttypes of blockchain nodes/peers may be present in the blockchain networkincluding endorsing peers which simulate and endorse transactionsproposed by clients and committing peers which verify endorsements,validate transactions, and commit transactions to the distributed ledger730. In this example, the blockchain nodes 721, 722, and 723 may performthe role of endorser node, committer node, or both.

The distributed ledger 730 includes a blockchain 732 which storesimmutable, sequenced records in blocks, and a state database 734(current world state) maintaining a current state of the blockchain 732.One distributed ledger 730 may exist per channel and each peer maintainsits own copy of the distributed ledger 730 for each channel of whichthey are a member. The blockchain 732 is a transaction log, structuredas hash-linked blocks where each block contains a sequence of Ntransactions. Blocks may include various components such as shown inFIG. 7B. The linking of the blocks (shown by arrows in FIG. 7A) may begenerated by adding a hash of a prior block's header within a blockheader of a current block. In this way, all transactions on theblockchain 732 are sequenced and cryptographically linked togetherpreventing tampering with blockchain data without breaking the hashlinks. Furthermore, because of the links, the latest block in theblockchain 732 represents every transaction that has come before it. Theblockchain 732 may be stored on a peer file system (local or attachedstorage), which supports an append-only blockchain workload.

The current state of the blockchain 732 and the distributed ledger 732may be stored in the state database 734. Here, the current state datarepresents the latest values for all keys ever included in the chaintransaction log of the blockchain 732. Chaincode invocations executetransactions against the current state in the state database 734. Tomake these chaincode interactions extremely efficient, the latest valuesof all keys are stored in the state database 734. The state database 734may include an indexed view into the transaction log of the blockchain732, it can therefore be regenerated from the chain at any time. Thestate database 734 may automatically get recovered (or generated ifneeded) upon peer startup, before transactions are accepted.

Endorsing nodes receive transactions from clients and endorse thetransaction based on simulated results. Endorsing nodes hold smartcontracts which simulate the transaction proposals. When an endorsingnode endorses a transaction, the endorsing nodes creates a transactionendorsement which is a signed response from the endorsing node to theclient application indicating the endorsement of the simulatedtransaction. The method of endorsing a transaction depends on anendorsement policy which may be specified within chaincode. An exampleof an endorsement policy is “the majority of endorsing peers mustendorse the transaction”. Different channels may have differentendorsement policies. Endorsed transactions are forward by the clientapplication to ordering service 710.

The ordering service 710 accepts endorsed transactions, orders them intoa block, and delivers the blocks to the committing peers. For example,the ordering service 710 may initiate a new block when a threshold oftransactions has been reached, a timer times out, or another condition.In the example of FIG. 7A, blockchain node 722 is a committing peer thathas received a new data block 750 for storage on blockchain 730.

The ordering service 710 may be made up of a cluster of orderers. Theordering service 710 does not process transactions, smart contracts, ormaintain the shared ledger. Rather, the ordering service 710 may acceptthe endorsed transactions and specifies the order in which thosetransactions are committed to the distributed ledger 730. Thearchitecture of the blockchain network may be designed such that thespecific implementation of ‘ordering’ (e.g., Solo, Kafka, BFT, etc.)becomes a pluggable component.

Transactions are written to the distributed ledger 730 in a consistentorder. The order of transactions is established to ensure that theupdates to the state database 734 are valid when they are committed tothe network. Unlike a cryptocurrency blockchain system (e.g., Bitcoin,etc.) where ordering occurs through the solving of a cryptographicpuzzle, or mining, in this example the parties of the distributed ledger730 may choose the ordering mechanism that best suits that network.

When the ordering service 710 initializes a new block 750, the new block750 may be broadcast to committing peers (e.g., blockchain nodes 721,722, and 723). In response, each committing peer validates thetransaction within the new block 750 by checking to make sure that theread set and the write set still match the current world state in thestate database 734. Specifically, the committing peer can determinewhether the read data that existed when the endorsers simulated thetransaction is identical to the current world state in the statedatabase 734. When the committing peer validates the transaction, thetransaction is written to the blockchain 732 on the distributed ledger730, and the state database 734 is updated with the write data from theread-write set. If a transaction fails, that is, if the committing peerfinds that the read-write set does not match the current world state inthe state database 734, the transaction ordered into a block will stillbe included in that block, but it will be marked as invalid, and thestate database 734 will not be updated.

Referring to FIG. 7B, a block 750 (also referred to as a data block)that is stored on the blockchain 732 of the distributed ledger 730 mayinclude multiple data segments such as a block header 760, block data770, and block metadata 780. It should be appreciated that the variousdepicted blocks and their contents, such as block 750 and its contents.shown in FIG. 7B are merely for purposes of example and are not meant tolimit the scope of the example embodiments. In some cases, both theblock header 760 and the block metadata 780 may be smaller than theblock data 770 which stores transaction data, however this is not arequirement. The block 750 may store transactional information of Ntransactions (e.g., 100, 500, 1000, 2000, 3000, etc.) within the blockdata 770. The block 750 may also include a link to a previous block(e.g., on the blockchain 732 in FIG. 7A) within the block header 760. Inparticular, the block header 760 may include a hash of a previousblock's header. The block header 760 may also include a unique blocknumber, a hash of the block data 770 of the current block 750, and thelike. The block number of the block 750 may be unique and assigned in anincremental/sequential order starting from zero. The first block in theblockchain may be referred to as a genesis block which includesinformation about the blockchain, its members, the data stored therein,etc.

The block data 770 may store transactional information of eachtransaction that is recorded within the block 750. For example, thetransaction data may include one or more of a type of the transaction, aversion, a timestamp, a channel ID of the distributed ledger 730, atransaction ID, an epoch, a payload visibility, a chaincode path (deploytx), a chaincode name, a chaincode version, input (chaincode andfunctions), a client (creator) identify such as a public key andcertificate, a signature of the client, identities of endorsers,endorser signatures, a proposal hash, chaincode events, response status,namespace, a read set (list of key and version read by the transaction,etc.), a write set (list of key and value, etc.), a start key, an endkey, a list of keys, a Merkel tree query summary, a user devicebiometric authentication, a file creator biometric authentication, asource file signature, an auxiliary data signature, a timestampassociated with a source file, and the like. The transaction data may bestored for each of the N transactions.

In some embodiments, the block data 770 may also store data 772 whichadds additional information to the hash-linked chain of blocks in theblockchain 732. Accordingly, the data 772 can be stored in an immutablelog of blocks on the distributed ledger 730. Some of the benefits ofstoring such data 772 are reflected in the various embodiments disclosedand depicted herein.

The block metadata 780 may store multiple fields of metadata (e.g., as abyte array, etc.). Metadata fields may include signature on blockcreation, a reference to a last configuration block, a transactionfilter identifying valid and invalid transactions within the block, lastoffset persisted of an ordering service that ordered the block, and thelike. The signature, the last configuration block, and the orderermetadata may be added by the ordering service 710. Meanwhile, acommitter of the block (such as blockchain node 722) may addvalidity/invalidity information based on an endorsement policy,verification of read/write sets, and the like. The transaction filtermay include a byte array of a size equal to the number of transactionsin the block data 770 and a validation code identifying whether atransaction was valid/invalid.

FIG. 8 is not intended to suggest any limitation as to the scope of useor functionality of embodiments of the application described herein.Regardless, the computing node 800 is capable of being implementedand/or performing any of the functionality set forth hereinabove.

In computing node 800 there is a computer system/server 802, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 802 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 802 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 802 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 8, computer system/server 802 in cloud computing node800 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 802 may include, but are notlimited to, one or more processors or processing units 804, a systemmemory 806, and a bus that couples various system components includingsystem memory 806 to processor 804.

The bus represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 802 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 802, and it includes both volatileand non-volatile media, removable and non-removable media. System memory806, in one embodiment, implements the flow diagrams of the otherfigures. The system memory 806 can include computer system readablemedia in the form of volatile memory, such as random-access memory (RAM)810 and/or cache memory 812. Computer system/server 802 may furtherinclude other removable/non-removable, volatile/non-volatile computersystem storage media. By way of example only, storage system 814 can beprovided for reading from and writing to a non-removable, non-volatilemagnetic media (not shown and typically called a “hard drive”). Althoughnot shown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to thebus by one or more data media interfaces. As will be further depictedand described below, memory 806 may include at least one program producthaving a set (e.g., at least one) of program modules that are configuredto carry out the functions of various embodiments of the application.

Program/utility 816, having a set (at least one) of program modules 818,may be stored in memory 806 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 818 generally carry out the functionsand/or methodologies of various embodiments of the application asdescribed herein.

As will be appreciated by one skilled in the art, aspects of the presentapplication may be embodied as a system, method, or computer programproduct. Accordingly, aspects of the present application may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present application may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Computer system/server 802 may also communicate with one or moreexternal devices 820 such as a keyboard, a pointing device, a display822, etc.; one or more devices that enable a user to interact withcomputer system/server 802; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 802 to communicate withone or more other computing devices. Such communication can occur viaI/O interfaces 824. Still yet, computer system/server 802 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 826. As depicted, network adapter 826communicates with the other components of computer system/server 802 viaa bus. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 802. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Although an exemplary embodiment of at least one of a system, method,and non-transitory computer readable medium has been illustrated in theaccompanied drawings and described in the foregoing detaileddescription, it will be understood that the application is not limitedto the embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions as set forth and defined by thefollowing claims. For example, the capabilities of the system of thevarious figures can be performed by one or more of the modules orcomponents described herein or in a distributed architecture and mayinclude a transmitter, receiver or pair of both. For example, all orpart of the functionality performed by the individual modules, may beperformed by one or more of these modules. Further, the functionalitydescribed herein may be performed at various times and in relation tovarious events, internal or external to the modules or components. Also,the information sent between various modules can be sent between themodules via at least one of: a data network, the Internet, a voicenetwork, an Internet Protocol network, a wireless device, a wired deviceand/or via plurality of protocols. Also, the messages sent or receivedby any of the modules may be sent or received directly and/or via one ormore of the other modules.

One skilled in the art will appreciate that a “system” could be embodiedas a personal computer, a server, a console, a personal digitalassistant (PDA), a cell phone, a tablet computing device, a smartphoneor any other suitable computing device, or combination of devices.Presenting the above-described functions as being performed by a“system” is not intended to limit the scope of the present applicationin any way but is intended to provide one example of many embodiments.Indeed, methods, systems and apparatuses disclosed herein may beimplemented in localized and distributed forms consistent with computingtechnology.

It should be noted that some of the system features described in thisspecification have been presented as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom verylarge-scale integration (VLSI) circuits or gate arrays, off-the-shelfsemiconductors such as logic chips, transistors, or other discretecomponents. A module may also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, graphics processing units, or thelike.

A module may also be at least partially implemented in software forexecution by various types of processors. An identified unit ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions that may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module. Further, modules may bestored on a computer-readable medium, which may be, for instance, a harddisk drive, flash device, random access memory (RAM), tape, or any othersuch medium used to store data.

Indeed, a module of executable code could be a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, and across several memorydevices. Similarly, operational data may be identified and illustratedherein within modules and may be embodied in any suitable form andorganized within any suitable type of data structure. The operationaldata may be collected as a single data set or may be distributed overdifferent locations including over different storage devices, and mayexist, at least partially, merely as electronic signals on a system ornetwork.

It will be readily understood that the components of the application, asgenerally described and illustrated in the figures herein, may bearranged and designed in a wide variety of different configurations.Thus, the detailed description of the embodiments is not intended tolimit the scope of the application as claimed but is merelyrepresentative of selected embodiments of the application.

One having ordinary skill in the art will readily understand that theabove may be practiced with steps in a different order, and/or withhardware elements in configurations that are different than those whichare disclosed. Therefore, although the application has been describedbased upon these preferred embodiments, it would be apparent to those ofskill in the art that certain modifications, variations, and alternativeconstructions would be apparent.

While preferred embodiments of the present application have beendescribed, it is to be understood that the embodiments described areillustrative only and the scope of the application is to be definedsolely by the appended claims when considered with a full range ofequivalents and modifications (e.g., protocols, hardware devices,software platforms etc.) thereto.

What is claimed is:
 1. A system, comprising: a blockchain networkcomprising a shared ledger which stores a source file signature that iscreated by inputting a plurality of segments of a source file pairedwith a plurality auxiliary data segments, respectively, into a firstMerkle tree of a chameleon hash function; a file redaction deviceconfigured to redact a source file segment from among the plurality ofsegments of the source file; a signature update device configured to:receive the redacted source file segment and the plurality of auxiliarydata segments paired with the plurality of segments of the source filein the chameleon hash function; modify an auxiliary data segment that ispaired with the redacted source file segment; input the plurality ofauxiliary data segments including the modified auxiliary data segmentinto a second Merkle tree of a cryptographic hash function which outputsa modified auxiliary data signature; and store the modified auxiliarydata signature to the shared ledger.
 2. The system of claim 1, whereinthe file redaction device is further configured to perform biometricauthentication on a user who redacted the source file segment.
 3. Thesystem of claim 2, wherein the file redaction device is furtherconfigured to: determine the user who redacted the source file segmenthas an approved identity; and create an authentication blockchaintransaction, the authentication transaction comprising biometricauthentications of the user who redacted the source file segment;wherein the blockchain network is configured to: endorse theauthentication transaction; and store the authentication transaction tothe shared ledger.
 4. The system of claim 1, wherein the plurality ofauxiliary data segments are stored outside the blockchain network. 5.The system of claim 1, wherein the source file signature previouslystored to the shared ledger does not change in response to the modifiedauxiliary data signature and the source file signature corresponds tooriginal source file content prior to redaction.
 6. The system of claim1, wherein the signature update device is configured to input theplurality of auxiliary data segments including the modified auxiliarydata segment into leaf nodes of the second Merkle tree.
 7. The system ofclaim 1, wherein the signature update device is further configured to:create a blockchain transaction comprising the modified auxiliary datasignature and an identifier of the redacted source file segment; whereinthe blockchain network is further configured to endorse the blockchaintransaction.
 8. A method, comprising: storing a source file signaturethat is created by inputting a plurality of segments of a source filepaired with a plurality auxiliary data segments, respectively, into afirst Merkle tree of a chameleon hash function; redacting, by a fileredaction device, a source file segment from among the plurality ofsegments of the source file; receiving, by a signature update device,the redacted source file segment and the plurality of auxiliary datasegments paired with the plurality of source file segments in thechameleon hash function; modifying an auxiliary data segment that ispaired with the redacted source file segment; inputting the plurality ofauxiliary data segments including the modified auxiliary data segmentinto a second Merkle tree of a cryptographic hash function which outputsa modified auxiliary data signature; and storing the modified auxiliarydata signature to a shared ledger of a blockchain network.
 9. The methodof claim 8, wherein the method further comprises: performing, by thefile redaction device, biometric authentication on a user who redactedthe source file segment.
 10. The method of claim 9, wherein the methodfurther comprises: determining the user who redacted the source filesegment has an approved identity; and creating an authenticationblockchain transaction, the authentication transaction comprisingbiometric authentications of the user who redacted the source filesegment; wherein the method further comprises: endorsing theauthentication transaction; and storing the authentication transactionto the shared ledger.
 11. The method of claim 8, wherein the pluralityof auxiliary data segments are stored outside the blockchain network.12. The method of claim 8, wherein the source file signature previouslystored to the shared ledger does not change in response to the modifiedauxiliary data signature and the source file signature corresponds tooriginal source file content prior to redaction.
 13. The method of claim8, wherein the inputting comprises inputting the plurality of auxiliarydata segments including the modified auxiliary data segment into leafnodes of the second Merkle tree.
 14. The method of claim 8, wherein thestoring comprises: creating a blockchain transaction comprising themodified auxiliary data signature and an identifier of the redactedsource file segment; and endorsing the blockchain transaction.
 15. Anon-transitory computer readable medium comprising instructions, thatwhen read by a processor, cause the processor to perform a methodcomprising: storing a source file signature that is created by inputtinga plurality of segments of a source file paired with a pluralityauxiliary data segments, respectively, into a first Merkle tree of achameleon hash function; redacting, by a file redaction device, a sourcefile segment from among the plurality of segments of the source file;receiving, by a signature update device the redacted source file segmentand the plurality of auxiliary data segments paired with the pluralityof source file segments in the chameleon hash function; modifying anauxiliary data segment that is paired with the redacted source filesegment; inputting the plurality of auxiliary data segments includingthe modified auxiliary data segment into a second Merkle tree of acryptographic hash function which outputs a modified auxiliary datasignature; and storing the modified auxiliary data signature to a sharedledger of a blockchain network.
 16. The non-transitory computer readablemedium of claim 15, wherein the method further comprises: determining auser who redacted the source file segment has an approved identity; andcreating an authentication blockchain transaction, the authenticationtransaction comprising a biometric authentication of the user whoredacted the source file segment; wherein the method further comprises:endorsing the authentication transaction; and storing the authenticationtransaction to the shared ledger.
 17. The non-transitory computerreadable medium of claim 15, wherein the plurality of auxiliary datasegments are stored outside the blockchain network.
 18. Thenon-transitory computer readable medium of claim 15, wherein the sourcefile signature previously stored to the shared ledger does not change inresponse to the modified auxiliary data signature and the source filesignature corresponds to original source file content prior toredaction.
 19. The non-transitory computer readable medium of claim 15,wherein the inputting comprises inputting the plurality of auxiliarydata segments including the modified auxiliary data segment into leafnodes of the second Merkle tree.
 20. The non-transitory computerreadable medium of claim 15, wherein the storing comprises: creating ablockchain transaction comprising the modified auxiliary data signatureand an identifier of the redacted source file segment; and endorsing theblockchain transaction.